Most boiler faults are inconvenient. A small number are not, and the difference matters because the dangerous ones do not always announce themselves loudly. A boiler that is burning badly can go on running, producing heat and hot water, while doing something nobody in the house can smell.
Derek Stuart Heating & Gas works as a boiler engineer across Whitley Bay, and this article is the short list worth knowing in advance: what to look at, what it means, and which category each fault belongs in.
What a healthy appliance looks like
Gas burns blue. A crisp, steady blue flame is what correct combustion looks like on a boiler, a fire or a cooker, and it is the baseline everything else is measured against.
A lazy yellow or orange flame is the classic sign that combustion has gone wrong. It means the appliance is not getting the air it needs, or something is obstructing the burner or the flue, and it is the visual signature of incomplete combustion.
The same is true of the marks an appliance leaves behind. Sooty or black staining around a boiler case, a fire surround or a flue terminal is evidence of something that should not be happening, and it does not clean itself up.
Excess condensation in a room whenever the appliance runs belongs in the same group. Combustion products should leave through the flue, and when they are appearing in the room instead, that is what is being told to you.
- Crisp blue flame: correct combustion.
- Yellow or orange, lazy flame: stop using it and get it checked.
- Sooty or black staining around an appliance or flue: not cosmetic.
- Unusual condensation whenever the appliance runs: combustion products in the room.
The symptoms people mistake for a virus
Carbon monoxide has no smell, no colour and no taste, so the human warning system is the symptoms it produces, and those look like ordinary illness. Headaches, dizziness, nausea, breathlessness and unexplained tiredness are the common ones.
The pattern is what distinguishes it. Symptoms that improve when you leave the house and return when you come back, or that affect more than one person in the household at the same time, or that appear when the heating is on and fade when it is off, all deserve immediate attention rather than a wait-and-see.
An audible carbon monoxide alarm is inexpensive and it detects what nobody can sense. It is worth having near any gas appliance and in rooms where people sleep, and worth testing rather than assuming the battery is fine.
If an alarm sounds, or if the pattern above matches what people in the house have been feeling, the sequence is: stop using the appliance, ventilate, get out, and get it looked at before it is used again.
The immediate actions, in order
For a suspected combustion problem, turn the appliance off and stop using it. Open windows and doors to ventilate the space. Do not restart it to see whether it does it again.
If you smell gas, the procedure is different and more urgent. Do not touch electrical switches or anything that could create a spark, turn the gas off at the meter control valve if you can reach it safely, open doors and windows, leave the property and call the national gas emergency service from outside. That call comes before any repair conversation.
Either way, do not have anybody unqualified investigate. Gas work is a regulated category, and Derek Stuart Heating & Gas is Gas Safe registered under Gas Safe 542871, which is the credential worth confirming for anyone you let near a gas appliance.
When you do book, say plainly what you saw. Flame colour, staining, condensation, smell, and whether anybody has felt unwell are the details that determine how the call is prioritised.
- Suspected bad combustion: stop using it, ventilate, get it checked before restarting.
- Smell of gas: no switches, no sparks, gas off if safe, leave, call from outside.
- Never let unregistered hands work on a gas appliance.
- Describe flame colour, staining and any symptoms when you book.
The faults that can wait for a normal appointment
Most things a boiler does are not in the categories above, and it helps to know which ones are simply annoying. A single lockout that resets and runs normally afterwards, a slow drop in pressure over weeks, one radiator that will not warm, or a boiler that has become slightly noisier are all ordinary faults for an ordinary appointment.
They are still worth reporting rather than absorbing. A pressure gauge that keeps falling means water is escaping somewhere, and repeated topping up brings fresh oxygenated water into the system, which accelerates corrosion inside it.
Fault diagnosis looks at error codes, pressure behaviour, thermostats, valves, circulation and visible wear, so the more of those you can describe, the more likely the first visit is also the last one.
The genuine dividing line is combustion and gas. Anything that suggests either is not a fault to live with while you decide; everything else can be planned.
Related pages
Questions customers ask
What colour should the flame on my boiler be?
Crisp blue. A lazy yellow or orange flame indicates incomplete combustion, which means the appliance should be turned off and checked before it is used again. The same applies to a gas fire or a gas cooker.
How would I know if there was carbon monoxide in the house?
Without an alarm you would be relying on symptoms, which resemble ordinary illness: headaches, dizziness, nausea and tiredness. The telling pattern is symptoms that ease when you leave the property and return when you come back, or that affect several people at once.
What should I do if I smell gas?
Do not touch electrical switches or anything that could spark. Turn the gas off at the meter if you can do so safely, open doors and windows, leave the property, and call the national gas emergency service from outside before arranging any repair.
Blue flame, no soot, no unexplained condensation, nobody feeling unwell when the heating runs. If any of those four change, the appliance stops being used until somebody qualified has looked at it.
Derek Stuart Heating & Gas covers boiler engineer work in Whitley Bay and is Gas Safe registered. The contact page is the place to report anything on this list.
